1. Field
The present disclosure relates to a hydraulic control device for an automatic transmission.
2. Description of the Related Art
In general, an automatic transmission includes an engagement mechanism such as a planetary gear mechanism, a clutch, and a brake, and achieves each of shift stages by switching between power transmission paths with the engagement mechanisms. In order to reliably perform switching between shift stages, the operation of the engagement mechanism is confirmed in some cases. After the operation is confirmed, the subsequent control is performed, whereas when the operation cannot be confirmed, it is determined that abnormality such as a fault has occurred and the abnormality is dealt with. It is typical that the operation confirmation is made by using a sensor specific to the engagement mechanism. It has been proposed that in a hydraulic control device that achieves engagement by hydraulic pressure, the hydraulic pressure supplied to an engagement mechanism be monitored by a hydraulic pressure sensor or the like to perform the operation confirmation (for example, Japanese Patent No. 5123130).
In Japanese Patent No. 5123130, in the case where “source pressure cut-off valve”, which is provided in case of on-fail of a linear solenoid valve, is stuck, a state of the stuck of “the source pressure cut-off valve” is detected and a source pressure cut-off switching valve is further provided.